An underground sexual fetish which involves one partner (the feeder) feeding the other, both to obtain sexual arousal and to encourage weight gain in the feedee. Feederism can vary in nature, from a consensual act between two people who mutually appreciate a larger body type, to non-consensual abuse, which may involve force-feeding and bondage and is undertaken with the intention of fattening up the feedee to the point of immobility and total dependence. The weight gained can also vary froma few pounds to hundreds, whilst some feeder relationships are not undertaken with the purpose of weight gain at all but for the enjoyment of food in an intimate context.

Most feedees are female (BBW or SSBBW) whilst the feeders tend to be FA males, although this is not the case, and gay/lesbian feeder relationships are not entirely unheard of.